In general, a sensitive material has an outermost layer (surface layer) which contains as a binder a certain hydrophilic organic colloid whose representative is gelatin. Therefore, the sensitive material shows an increase in its adhesiveness or tackiness under circumstances of high temperature and humidity, whereby adhesion occurs readily when the sensitive material is allowed to stand in contact with another object.
This adhesion phenomenon occurs between sensitive materials, or between a sensitive material and a different material placed in contact therewith upon production of the sensitive material or during storage, photographing, processing or projection, or during preservation of the processed sensitive material, and it often causes serious disadvantages.
It is well-known in this art that in order to solve this problem an inorganic substance such as silicon dioxide, magnesium oxide, titanium dioxide, calcium carbonate or the like, or fine grains of an organic substance such as polymethyl methacrylate, cellulose acetate propionate or the like (which are called "matting agent" hereinafter) is incorporated in the topmost layer of a sensitive material and thereby the surface of the sensitive material is increased in its roughness, that is to say, it is matted and reduces its adhesiveness.
In some cases it is desired to remove a matting agent for the purposes of improving transparency and graininess properties of formed images. Such a method is described in U.S. Pat. No. 4,142,894, which describes methyl methacrylate-methacrylic acid copolymers intended to be soluble in an alkaline processing solution at a temperature above 30.degree. C. On the other hand, in other photographic materials it is desired to retain the matting agent to prevent the adhesion phenomenon after developing, and to prevent removal of matting agent and related problems during image development processing.
On the other hand, recent development-processing techniques for sensitive materials have been increasingly rapid. In proportion, as the processing time becomes shorter, the sensitive material carries a larger amount of processing solution used in the previous processing step into the processing bath subsequent thereto and, consequently, the processability of the processing bath deteriorates more rapidly. In addition, an increased water content in the final processing bath imposes heavier load on the drying system, and, consequently, makes a rapid processing more difficult.
Under these circumstances, various devices have been tried with the intention of reducing the quantity of a processing solution which is carried out of the processing bath used in one step into another processing bath to be used in the following step.
For instance, in the case that a number of narrow belt-form films, such as color sensitive materials having a width of 35 mm, are linked up one after another, and subjected continuously to a chain of processings, a rubber plate for removing excess liquid (which is referred to as a "rubber lip" hereinafter) has been set up between each pair of processing baths arranged in order and/or behind the last processing bath, and the sensitive materials are drawn through the rubber lips and thereby the processing solutions adhering to the sensitive material are scraped off respectively. In another case that sheet-form sensitive materials, such as X-ray sensitive materials, are processed, a pair of counter rollers is set up between every pair of processing baths arranged in order and/or behind the last processing bath, and the sensitive materials are drawn through pairs of rollers and thereby the processing solutions adhering to the sensitive material are squeezed respectively. Rollers used for this purpose are called "squeeze rollers". Furthermore, "buff rollers" can be also used to remove excess processing solutions from the sensitive materials.
Thus, as a chain of processings of sensitive materials is carried out at higher speed, the extent of damage from abrasion which is caused in the surface of a sensitive material by the sensitive material being passed through the rubber lips, the squeeze rollers or the buff rollers becomes more drastic.
When the surface of a sensitive material is rubbed severely with rubber lips, squeeze rollers or buff rollers, problems such that matting agent present in the outermost layer is removed from the layer are apt to be caused.
Removal of the matting agent due to passage through rubber lips or squeeze rollers results in a low degree of matting for the sensitive material after the completion of a chain of processings, and tends to cause adhesion between sensitive materials or between the sensitive material and other materials and thereby causing various problems. Furthermore, upon contact exposure of another unexposed sensitive material through the sensitive material having received processings in the above-described manner there is a possibility of generation of the so-called "Newton ring" due to a low degree of matting (the extent of matting is expressed in the term of "mat property" hereinafter).
More importantly, removed particles of the matting agent are accumulated, aggregate, grow into huge grains, and some of resulting huge grains of the matting agent are transferred onto the surfaces of other sensitive materials.
Adhesion of such huge grains to the surfaces of sensitive materials makes the sensitive materials dirty and causes severe damage to the quality of the sensitive materials finished processings.
Furthermore, the huge grains of a matting agent accumulated on the surface of a rubber lip or a squeeze roller impair the surface of a sensitive material conveyed with a high speed, and in some cases may make scratches on the surface of the sensitive material.
A scratch having once been generated, a lot of defective materials are produced for a short time because of high processing and conveying speeds, to result in a heavy loss.
In addition, although fine grains of silicon dioxide have generally been employed as a matting agent in this art, such a matting agent suffer from the defect that it is impossible to control their average grain size to the degree desired.
Moreover, fine grains of silicon dioxide are likely to adhere to wall surfaces of a dissolution tank and so on in the step of preparing a coating solution for making a hydrophilic colloidal layer of a sensitive material, for example, a surface protecting layer and, therefore, they suffer from a troublesome disadvantage that the cleaning work in the preparation step requires extensive labor.